The present invention relates to water filtration devices, which include a cyst-reducing water filter capable of reducing parasites and other impurities in drinking water and yet capable of delivering a substantial water flow rate at relatively low (gravity-assisted) water pressures. While the invention may be used in other types of water filtration devices, it is especially suited for use in existing gravity-flow water carafes, and will be particularly described in that connection.
Until recently, water filter carafes of commercially available design have not been capable of parasite reduction, which requires much finer filtration. Nor have they been effective for the significant reduction of organic chemicals, pesticides and insecticides, which requires more carbon. While such additional removal attributes are desirable, they have not been technically feasible in the filter sizes required and at the filter cost currently available in the market. In addition to the concerns about drinking water taste and odor, consumers are beginning to be more concerned with the quality of drinking water, thus increasing the demand for gravity-flow filter carafes. This is because such water filter carafes are relatively low in cost and operate in a simple manner. Water from a tap is simply poured into the top of the filtration unit and is allowed to flow through a replaceable filter cartridge to a treated water reservoir for later use. A typical commercially available cyst-reducing water filter cartridge consists of a filter housing which contains a packed bed mixture of ion-exchange resin for the removal of unwanted ions, for example, lead, copper, and hard water ions, as well as carbon granules for the removal of adsorbable/catalyzable constituents such as chlorine and undesirable tastes and odors. Further, the filter housing contains a high surface area cyst-reducing filter element that is capable of removing harmful parasites and dirt that are present in water from a municipal water source. Without the cyst-reducing filter element, the housing containing the packed bed mixture that is commercially available for use in gravity-flow water carafes typically have physical volumes on the order of 165 cm3 (10 in3). This suggests that a filter incorporating the additional cyst function using the current designs would require more volume than that mentioned above. Gravity cyst-reducing filters should be able to achieve the production of a reasonable quantity of filtered water in a reasonable time, preferably, approximately 1 liter in less than 12 minutes.
Although filter designs and materials capable of effective cyst reduction exist, many households currently utilize water carafes that are not capable of cyst reduction. Consumers who have already invested in a water filter carafe that is capable of filtering out lead, copper and zinc as well as removing undesirable tastes and odors are reluctant to discard their existing water filter carafe for a more recently available cyst-reducing filter, since they would lose their original investment and moreover add to already overcrowded landfills.
In light of the foregoing, it is desirable to provide a cyst-reducing water filtration device that can be used in conjunction with an existing carafe system and that can deliver an adequate filter flow rate at relatively low (gravity-flow or gravity-assisted) water pressures. In addition, it is desirable to provide a water filtration device that can be easily attached to an existing water filter carafe in order to convert the carafe to an effective cyst-reducing water filter carafe, providing at least 99.95% removal of 3-4 xcexcm particles from a raw water source when tested in accordance with NSF Standard 53, Drinking Water Treatment Unitsxe2x80x94Health Effects (September 1997). Furthermore, it is desirable to provide a replaceable and affordable water filtration device for reducing cysts in drinking water as well as a filtration device that can be separated from the other components of the filtration device.
Accordingly, the present invention is directed to a water filtration device and a method of converting a gravity-flow water filtration device into a cyst-reducing water filtration device that substantially obviates one or more of the limitations and disadvantages of the related art. The principal advantage of the present invention is the provision of an arrangement that overcomes the limitations and disadvantages of the described prior arrangements. Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the apparatus particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the water filtration device is a replaceable gravity-flow cyst-reducing water filtration member for use in a water filter carafe that already has the capability of removing tastes and odors. In particular, the water filtration device comprises a removable high surface area cyst-reducing filtration member that provides at least 99.95% removal of 3-4 xcexcm particles when tested in accordance with NSF standard 53, Drinking Water Treatment Unitsxe2x80x94Health Effects (September 1997). The cyst-reducing filtration member is adapted for connection to a bottom rim of a filtration cartridge sleeve of a water filter carafe, the cartridge sleeve being integral with a bottom surface of an untreated water reservoir of the water filter carafe. The cartridge sleeve further comprises an air vent hole that is located proximate to a top rim of the cartridge sleeve, wherein the cartridge sleeve further contains a filtration cartridge that is filled with an ion-exchange resin and carbon granules. The filtration cartridge further has at least one untreated water inlet port located in a cap that is attached to the filtration cartridge at a top end, and at least one treated water outlet port located at a bottom end of the filtration cartridge, wherein the untreated water inlet port of the filtration cartridge is in fluid communication with the untreated water reservoir of the water filter carafe, and wherein the cyst-reducing filtration member is in fluid communication with the treated water outlet port of the filtration cartridge. Further, the water filtration device comprises a membrane that is adapted for attachment to the air vent hole. The membrane has at least one hydrophobic side, which hydrophobic side faces the inside of the cartridge sleeve upon attachment. The water filtration device further comprises sealing means for forming a water-tight seal between the cyst-reducing filtration member and the cartridge sleeve of the carafe.
In one embodiment of the invention, the sealing means comprises a gasket that is permanently attached to the outside periphery of the cyst-reducing filtration member to provide a water-tight seal. In another embodiment of the invention, the sealing means comprises an annular member with an upper surface and a lower surface and a gasket, wherein the annular member is permanently connected to the outside periphery of the cyst-reducing filtration member, and wherein the gasket abuts against the annular member. In yet another embodiment, the sealing means comprises an annular rim attached proximate to a topmost surface of the high surface area cyst-reducing filtration member, wherein the annular rim has an upright edge extending above a topmost surface of the high surface area cyst-reducing filtration member, and wherein the upright edge is adapted to receive the bottom rim of the cartridge sleeve. In a further embodiment, the sealing means further comprises an annular member with an integral groove and a gasket, wherein the annular member is permanently connected to the outside periphery of the cyst-reducing filtration member, and wherein the gasket is securely placed within the groove of the annular rim.
In each of the preferred embodiments, the removable high surface area cyst-reducing filtration member comprises a cellular honeycomb structure having a plurality of channels separated by porous channel walls, wherein the channels traverse the filtration member from a cyst-filled water inlet end to a cyst-removed water outlet end, and include a first plurality of channels open only at the cyst-filled water inlet end and a second plurality of channels open only at the cyst-removed water outlet end, and where the cellular honeycomb structure is made of ceramic. In an alternative embodiment, the cellular ceramic honeycomb structure further comprises activated carbon.
Furthermore, a method is provided for converting a gravity-flow water filtration carafe into a cyst-reducing water filtration carafe. In particular, the invention provides a method of converting a gravity-flow water filtration carafe having an integrally molded filtration cartridge sleeve containing a cartridge with an ion-exchange resin and carbon granules into a gravity-flow cyst-reducing filtration carafe. The cartridge sleeve includes an air vent hole proximate to a top rim of the cartridge sleeve. The method comprises the steps of connecting a high surface area cyst-reducing filtration member that provides at least 99.95% removal of 3-4 xcexcm particles when tested in accordance with NSF standard 53, Drinking Water Treatment Unitsxe2x80x94Health Effects (September 1997) to a bottom rim of the filtration cartridge sleeve, forming a water-tight seal between the filtration cartridge sleeve and the high surface area cyst-reducing filtration member and securing a membrane having at least one hydrophobic side across the air vent hole. In the preferred embodiment, the step of connecting involves connecting a cellular honeycomb structure having a plurality of channels separated by porous channel walls, wherein each of the channels traverse the structure from a cyst-filled water inlet end to a cyst-removed water outlet end, and include a first plurality of channels open only at the cyst-filled water inlet end and a second plurality of channels open only at the cyst-removed water outlet end. Further, the step of securing preferably includes positioning the hydrophobic side of the membrane toward the inside of said cartridge sleeve. Furthermore, in one embodiment of the invention, the step of forming a water-tight seal further comprises permanently attaching a gasket to the outside periphery of the cyst-reducing filtration member and inserting the cyst-reducing filtration member into the bottom rim of the cartridge sleeve. In another embodiment of the invention, the step of forming a water-tight seal farther comprises permanently attaching an annular member with an upper surface and a lower surface, and abuttingly placing a gasket against the upper surface of the annular member. In yet another embodiment, the step of forming a water-tight seal further comprises permanently attaching an annular member with an upper surface and a lower surface, and abuttingly placing a gasket against the lower surface of the annular member. In a further embodiment, the step of forming a water-tight seal further comprises attaching an annular member having an integral groove to the outside periphery of said cyst-reducing filtration member, and placing a gasket within said integral groove. Finally, in yet another embodiment of the invention, the step of forming a water-tight seal further comprises attaching an annular rim having an upright edge extending from a topmost surface of the high surface area cyst-reducing filtration member, and positioning the upright edge around the exterior surface of the bottom rim of the cartridge sleeve to form a water-tight seal.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrating embodiments of the invention, and together with the description serve to explain the objects, advantages, and principles of the invention.